1. Field of Invention
This invention relates to an acoustic probing technique for wear mitigation in a pipe, a pipeline or a liner of a pipe; and more particularly relates to a method and apparatus for determining coating wear or scale build-up and liner wear.
2. Description of Related Art
In a range of industrial applications, it can be important to assess the build up of an undesired coating, or the wear of an intentionally incorporated coating/liner on the inside of a process pipe line. For example:                1) In many processes scale deposits can build up on the interior of a pipe, and it is important to monitor this build up as these deposits can have detrimental effects on the throughput and performance of the process. Uncontrolled scale build up will typically result in a complete blockage of the pipe. Examples include areas such as pulp and paper processing plants, petro-chemical plants, and oil and gas distribution pipelines.        2) In many slurry and chemically aggressive applications, pipes are often coated with a liner to protect the inner pipe wall from corrosion and or erosion due to the flowing fluids, and knowledge of the thickness of these liners is important to ensure the integrity of the process-pipe or pipeline structure: As an example, to overcome the significant wear that can occur in pipelines carrying slurry materials such as in the oil sands industry, many suppliers are adopting pipes lined with materials, such as hard abrasion resistant materials such as chromium, or softer compliant elastomers such as urethanes.In both sets of examples given above, monitoring of the coating or liner on the inside of a pipe wall is important for the integrity of the process system.        
Ultrasonic non-destructive examination (NDE) approaches to detecting the thickness of a pipe wall are widely and successfully used in across industrial applications. By way of example, NDE sensors may be designed and configured to measure the pipe-wall thickness, e.g., including known techniques and monitoring devices provided in the marketplace in conjunction with the trademark HALO® system by the assignee of the instant patent application, can be used to monitor the performance of a so-called “sacrificial” coating and ensure that the steel wall is not being abraded significantly. By way of example, see the NDE techniques disclosed in PCT application No. PCT/US11/28957, filed 18 Mar. 2011, entitled “Method and Apparatus for Monitoring of Components Housing Wall Thickness and Wear Monitoring,” that claims benefit to provisional patent application No. 61/315,233, filed 18 Mar. 2010, which are both incorporated herein by reference in their entirety. See also the corresponding U.S. national stage patent application Ser. No. 13/635,449, filed 17 Sep. 2012, which is also incorporated herein by reference in its entirety.
Such NDE approaches may, however, not be highly effective for the detection of the thickness of coating on the interior of the pipe due to the poor impedance discrimination of the liner or lining and fluid material (as compared to a pipe wall—often steel—and the fluid, where the pipe does not have a liner). Consequently, monitoring the status of a lined pipe may be a challenge, and catastrophic failure can result if an incorporated lining is damaged and tears away from the outer steel pipe, exposing it directly to the fluid abrasion/corrosion, or if scale build-up rapidly escalates to block the pipe.
Further, another problem in the art relates to the need to overcome the significant wear that can occur in pipelines carrying slurry materials, particularly as in the oil sands industry, many suppliers are adopting ‘lined’ pipes, including where materials, such as urethanes and other elastomers, may be used. A good example is Irathance from a company named Iracore. These materials provide good resistance to abrasion, but ultrasonic NDE approaches for detecting the lining thickness are typically not effective due to the poor impedance discrimination of the lining and slurry material (as compared to a steel pipe wall (without a liner) and the slurry). Consequently, monitoring the status of a lined pipe can also be a challenge.
In view of this, there is a need in the industry to provide a better way for determining coating wear, or scale build-up, or liner wear.